Are U.S. app makers losing their competitive edge? According to new numbers from mobile analytics firm Flurry Analytics, more mobile apps are being built outside the U.S. than inside.

In 2011 and 2012, U.S. app makers controlled 45 percent of the apps developed worldwide. This year, that share has fallen to 36 percent.

U.S. app makers are still dominant in terms of active users and engagement, but that number is slipping as well.

In 2011 and 2012, 75 and 76 percent of active apps were created in the U.S., respectively. In 2013, that share fell to 70 percent.

Flurry also broke down the total time spent in apps by user country and the app's country of origin.

U.S.-made apps unsurprisingly enjoy the most use in the United States, and are the least used in China, where 64 percent of total time is spent on Chinese-made apps.

As TechCrunch notes, "the concern here is that U.S. developers have been slow to think about localization efforts, having ridden the app wave so far resting on the fact that English is one of the world's more dominant languages."

That assumption has given other countries a head start in globalizing their mobile apps, with developers in Finland, Denmark, Bulgaria and Slovenia localizing apps in markets outside their home market.